Adjustable shock absorber

ABSTRACT

A shock absorber assembly includes a damping adjustment mechanism that can easily be incorporated into a twin cylinder design. The shock absorber includes an outer cylinder and an inner cylinder mounted within the outer cylinder. The inner cylinder is spaced apart from the outer cylinder to define a gap. A piston is mounted within a fluid filled chamber formed within the inner cylinder to dampen vibrations. Holes are drilled into the wall of the inner cylinder to provide fluid ports that can communicate with the gap to form a bi-directional fluid path as the piston moves back and forth within the chamber to dampen vibrations. To provide variable damping, the outer cylinder includes an eccentric inner diameter to outer diameter profile that allows damping adjustment between high and low damping forces. The damping force is adjusted by rotating the outer cylinder relative to the inner cylinder to vary the size of the gap with respect to the ports.

BACKGROUND OF THE INVENTION

This invention relates to a device and method for adjusting damping in avehicle shock absorber.

Vehicles utilize shock absorbers to dampen vibrations and shocksexperienced by a vehicle. Variations in payload and ground conditionscan affect vehicle control and handling. Having the ability toselectively adjust the damping force in a shock absorber is desirable toimprove vehicle control and handling in response to these variables.Some shock absorbers include position sensing technology and dampingadjustment that permit a vehicle operator to selectively change dampingto a desired level.

Current adjustment systems rely on external components or adjustermodules to provide adjustment. Utilizing additional componentssignificantly increases cost and assembly time. Thus, the adjustmentfeature is not typically incorporated on most vehicles.

It is desirable to provide a shock absorber with an adjustment mechanismthat utilizes components already found within the shock absorber, andwhich can be easily adjusted by a vehicle operator to control dampinglevels. The adjustment mechanism should also be cost effective inaddition to overcoming the above referenced deficiencies with prior artsystems

SUMMARY OF THE INVENTION

The subject invention provides a shock absorber that includes dampingadjustment for a twin cylinder configuration having an inner cylindermounted within an outer cylinder in a spaced relationship to form a flowgap. Simultaneous and/or independent compression and rebound dampingadjustment is achieved by moving the outer cylinder with respect to theinner cylinder to adjust flow gap size around flow ports formed withinthe inner cylinder. The outer cylinder can be rotated or axiallytranslated relative to the inner cylinder to adjust gap size.

In the preferred embodiment, this is accomplished by the outer cylinderhaving an eccentric inner diameter to outer diameter profile to controlthe width of the flow gap is in relation to the ports. The outercylinder forms an outer wall of the shock absorber and the innercylinder forms an inner wall of the shock absorber. The outer wall isdefined by an outer diameter that has a first center and an innerdiameter that has a second center that is different than the firstcenter to form the eccentric profile. The eccentricity of the outer walladjusts flow gap size as the outer cylinder is rotated or translated toadjust damping. The eccentricity is formed by varying the wall thicknessor profile of the outer cylinder. Multiple eccentricities to providemultiple gap size variations are achieved by forming the outer wall withseveral different thicknesses about the circumference.

In one embodiment, the eccentricity is uniform such that the gap isuniform in cross-section along the length of the cylinders. The shockabsorber is adjustable between a low damping force where the gap size isdefined by a first width in relation to the ports and a high dampingforce where the gap size is defined by a second width in relation to theports that is less than the first width.

In an alternate embodiment, the eccentricity is variable such that thegap is nonuniform in cross-section along the length of the cylinders.The variable eccentricity results from an inner surface of the outerwall having a stepped or tapered profile. The steps or taper providevariable gap widths for each of the ports.

These and other features of the present invention can be best understoodfrom the following specification and drawings, the following of which isa brief description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a shock absorber incorporatingthe subject invention.

FIG. 2 is a cross-sectional cut-away view of a prior art shock absorber.

FIG. 3A is a cross-sectional cut-away view of a shock absorberincorporating the subject invention adjusted to a low damping position.

FIG. 3B is a cross-sectional cut-away view of the shock absorber of FIG.3A adjusted to in a high damping position.

FIG. 4A is a cross-sectional cut-away view of an alternate embodimentincorporating the subject invention adjusted to a low damping position.

FIG. 4B is a cross-sectional cut-away view of the shock absorber of FIG.4A adjusted to in a high damping position.

FIG. 5A is a cross-sectional cut-away view of an alternate embodimentincorporating the subject invention adjusted to a low damping position.

FIG. 5B is a cross-sectional cut-away view of the shock absorber of FIG.5A adjusted to in a high damping position.

FIG. 6A is a cross-section of one embodiment of the outer cylinder.

FIG. 6B is a cross-section of an alternate embodiment of the outercylinder.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

Referring to FIG. 1, a shock absorber assembly is shown generally at 10.The shock absorber 10 includes an outer cylinder 12 and an innercylinder 14 mounted within the outer cylinder 12 in a spacedrelationship to form a flow gap 16. The outer cylinder 12 forms an outerwall 18 of the shock absorber 10 and the inner cylinder 14 forms theinner wall 20 of the shock absorber 10.

The inner wall 20 defines a chamber 22 in which a plunger or pistonmember 24 is mounted. Fluid is sealed within the chamber 22, as is knownin the art, and is compressed by the piston 24 to dampen vibrations. Anytype of known fluid can be used, including hydraulic fluid or gas eitherof which could be compressible or incompressible, for example.

Multiple ports 26 are formed within the inner wall 20. The ports 26 arepreferably formed on only one side of the inner cylinder 14 to define aported side 28 and non-ported side 30 of the inner cylinder 14. Theports 26 allow fluid communication with the gap 16 as the piston 24moves within the chamber 22.

The piston 24 separates the chamber 22 into a compression side 22a and arebound side 22b. There are ports 26 positioned on both the compression22a and rebound 22b sides. As vibrations are dampened, fluid flows fromthe rebound side 22b to the compression side 22a and/or vice versa viathe ports 26 and gap 16. Thus, fluid flow can be bi-directional betweenthe rebound 22b and compression 22a sides or check valves can be used toallow fluid to flow in one direction while preventing fluid flow in anopposite direction. Fluid also flows back and forth between the rebound22b and compression 22a sides via disc valves (not shown) through thepiston 24 as known in the art. The operation of disc and check valves iswell known and will not be discussed in further detail.

The subject invention provides an adjustment mechanism for varying thedamping force of the shock absorber 10 that can be selectively actuatedby a vehicle operator. It is desirable to control damping force toprovide improved vehicle control and handling to accommodate vehiclepayload changes or ground condition changes. For example, one vehicleapplication in which shock absorber damping adjustment is desirable isfor snowmobiles. Aggressive drivers may desire high damping forces whilenon-aggressive drivers desire lower damping forces. Or, if more than onepassenger is riding on the snowmobile it may be desirable to change thedamping force to accommodate the additional weight.

Damping force adjustment is accomplished by selectively rotating oraxially translating the outer cylinder 12 with respect to the innercylinder 14 to vary the size of the gap 16 in relation to the ports 26.The rotation or translation of the outer cylinder 12 is accomplished byany of various types of actuation methods. For example, the outercylinder 12 can be manually moved by the operator or can be electricallymoved upon selection of a desired damping position by the operator.

For manual rotation or translation, a grip portion 32 can be formed onthe outer surface of the outer cylinder 12 and a label or markings 34can be made on the outer cylinder 12 to indicate various adjustmentpositions. The grip portion 32 can be positioned anywhere along thelength of the outer cylinder 12 and can be a separate member attached toor formed within the cylinder 12, as shown in FIG. 1, or can simply bedefined as any exterior surface presented by the outer cylinder 12.

For electrical rotation or translation, a controller and motor 36 can beselectively actuated by the operator to move the outer cylinder 12. Apush-button, switch, dial, or toggle (not shown) can be selected topower the system.

As discussed above, the damping adjustment occurs as a result ofvariation in flow gap size. One way to vary the flow gap size is byvarying the thickness or profile of the outer wall 18. In prior artsystems, shown in FIG. 2, the outer cylinder 12 was defined by a wall 40having equal thickness about the circumference of the cylinder 12. Withthis configuration the flow gap 16 has a constant and uniform widthbetween the inner 14 and outer 12 cylinders. As the piston 24 moves backand forth in the chamber 22, fluid flows back and forth between thecompression 22a and rebound 22b sides via the ports 26 and gap 16 andthere is a constant damping force.

As indicated above, in one embodiment the subject invention varies flowgap size by eccentrically forming the outer wall 18, as shown in FIGS.3-5. The outer wall 18 is defined by an outer diameter and an innerdiameter that have different centers creating an eccentric innerdiameter to outer diameter profile. This is accomplished by forming oneportion of the outer cylindrical wall 18 with greater thickness thananother portion of the wall 18, i.e. the wall thickness for the outerwall is non-uniform. A cross-section of the outer wall 18 is shown inFIG. 6A. In this embodiment, one side of the wall 18 is significantlythicker than the other side. The wall is formed with multipleeccentricities by varying the wall thickness between a maximum thicknessand a minimum thickness. Thus, the gap size can be infinitely varied asthe outer cylinder 12 is rotated anywhere between 0° to 180°.

An alternate embodiment for a cross-section of the outer cylinder 12 isshown in FIG. 6B. In this embodiment, the outer cylinder 12 is definedby an inner diameter that presents a variable profile. An example ofthis is shown in FIG. 6b in which the wall 18 includes multiple waves orsteps 38 formed on the inner surface to vary gap size between multiplewidths as the outer cylinder 12 is rotated between 0° to 180°.

Thus, the eccentric inner diameter to outer diameter profile changes theflow gap width in relation to the ports 26 to vary damping. It should beunderstood that while only two (2) ports 26 are shown in FIGS. 3-5,additional ports could also be formed within the inner wall 20.

In one embodiment, shown in FIGS. 3A and 3B, the gap size is uniform andconstant in cross-section along the longitudinal direction (length) ofthe cylinders 12, 14. Due to the eccentric formation of the outercylinder 12, the ported side 28 of the inner cylinder 14 defines a firstgap width in relation to the ports 26 and the non-ported side 30 of theinner cylinder 14 defines a second gap width between the inner 14 andouter 12 cylinders. In the low damping force configuration, shown inFIG. 3A, the first gap width is greater than the second gap width. Inthe high damping force configuration, shown in FIG. 3B, the outercylinder 12 is rotated such that the first gap width is less than thesecond gap width. Due to the decrease in gap width in relation to theports 26, less fluid can flow back and forth between the compression 22aand rebound 22b sides of the piston 24 as compared to the amount offluid flowing in the low damping configuration.

In an alternate embodiment, shown in FIGS. 4A and 4B, the outer cylinder12 includes a stepped surface to provide variable gap widths fordifferent ports 26. In this embodiment, the outer cylinder 12 is definedby a wall 50 having a stepped inner surface 52. In this embodiment, thegap 16 is non-uniform and variable along the longitudinal direction ofthe cylinders 12, 14. The gap widths for each port 26 in relation to thestepped inner surface are different with respect to each other. Forexample, a first gap width 54a is defined between one of the ports 26aand the outer cylinder 12 and a second gap width 54b is defined betweenanother of the ports 26b and the outer cylinder 12. A step 56 decreasesthe size of the first gap width 54a. A third gap width 54c is definedbetween the non-ported side 30 of the inner cylinder 14 and the outercylinder 12.

In the low damping force configuration, shown in FIG. 4A, the first gapwidth 54a is less than the second gap width 54b and both the first 54aand second 54b gap widths are greater than the third gap width 54c. Inthe high damping force configuration, shown in FIG. 4B, the outercylinder 12 is rotated or translated such that the first gap width 54aand the second gap widths 54b are both less than the third gap width54c. Due to the decrease in gap width in relation to the ports 26 in thehigh damping force position, less fluid can flow back and forth betweenthe compression 22a and rebound 22b sides of the piston 24 as comparedto the amount of fluid flowing in the low damping configuration. But, inthe low damping configuration, damping force is further adjusted byproviding different gap widths between each of the ports 26 and theouter cylinder 12. It should be understood that while two ports 26 areshown in FIGS. 4A and 4B, additional ports 26 and additional steps 56could be formed to provide further damping adjustment.

In an alternate embodiment, shown in FIGS. 5A and 5B, the outer cylinder12 includes a tapered surface to provide variable gap widths fordifferent ports 26. In this embodiment, the outer cylinder 12 is definedby a wall 60 having a tapered inner surface 62 providing multiplediameter changes along the length of the wall 60. In this embodiment,the gap 16 is non-uniform and variable along the longitudinal directionof the cylinders 12, 14. The gap widths for each port 26 in relation tothe tapered inner surface 62 are different with respect to each other.For example, a first gap width 64a is defined between one of the ports26a and the outer cylinder 12 and a second gap width 64b is definedbetween another of the ports 26b and the outer cylinder 12. The taperedsurface 62 decreases the size of the first gap width 64a in comparisonto the second gap width 64b. A third gap width 64c is defined betweenthe non-ported side 30 of the inner cylinder 14 and the outer cylinder12.

In the low damping force configuration, shown in FIG. 5A, the first gapwidth 64a is less than the second gap width 64b and both the first 64aand second 64b gap widths are greater than the third gap width 64c. Inthe high damping force configuration, shown in FIG. 5B, the outercylinder 12 is rotated or translated such that the first gap width 64aand the second gap width 64b are both less than the third gap width 64c.Due to the decrease in gap width in relation to the ports 26 in the highdamping force position, less fluid can flow back and forth between thecompression 22a and rebound 22b sides of the piston 24 as compared tothe amount of fluid flowing in the low damping configuration. But, inthe low damping configuration, damping force is further adjusted byproviding different gap widths between each of the ports 26 and theouter cylinder 12. It should be understood that while two ports 26 areshown in FIGS. 5A and 5B, additional ports 26 could be formed to providefurther damping adjustment.

The aforementioned description is exemplary rather that limiting. Manymodifications and variations of the present invention are possible inlight of the above teachings. The preferred embodiments of thisinvention have been disclosed. However, one of ordinary skill in the artwould recognize that certain modifications would come within the scopeof this invention. Hence, within the scope of the appended claims, theinvention may be practiced otherwise than as specifically described. Forthis reason the following claims should be studied to determine the truescope and content of this invention.

1. A shock absorber assembly comprising: a first cylinder having anouter wall with a thickness defined by a constant outer diameter and avariable inner diameter; a second cylinder mounted within said firstcylinder and having an inner wall enclosing a chamber, wherein saidfirst cylinder comprises an outermost shock absorber cylinder and saidsecond cylinder comprises an innermost shock absorber cylinder with saidinner wall being spaced apart from said outer wall to define a gapextending longitudinally between said first outermost and secondinnermost shock absorber cylinders; a piston mounted within said secondcylinder to separate said chamber into a rebound side and a compressionside, said piston being movable along a longitudinal path relative tosaid inner wall to dampen vibrations; a plurality of ports formed withinsaid inner wall to define a sealed fluid path wherein fluid flowsbi-directionally within said gap and into and out of said rebound andcompression sides of said chamber via said plurality of ports inresponse to said piston moving back and forth within said chamber; andan actuator for selectively adjusting the a damping force by axiallytranslating said outer wall relative to said inner wall in a directionparallel to said longitudinal path to vary the size of said gap.
 2. Theassembly according to claim 1 wherein said outer wall is defined by aninner diameter having a first center and an outer diameter having asecond center that is different than said first center to define aneccentric inner diameter to outer diameter profile for said outer wall.3. The assembly according to claim 2 wherein said gap is defined as aring-shaped gap, said gap having a variable cross-section along said alongitudinal direction.
 4. The assembly according to claim 3 whereinsaid inner wall has a ported portion and a non-ported portion with allof said plurality of ports being formed along said ported portion ofsaid inner wall and wherein said eccentric inner diameter to outerdiameter profile defines a first gap width between one of said pluralityof ports and said outer wall, a second gap width between another of saidplurality of ports and said outer wall, and a third gap width betweensaid non-ported portion of said inner wall and said outer wall, saidouter wall being longitudinally translated to adjust said first, second,and third gap widths to control the damping force.
 5. The assemblyaccording to claim 4 wherein said outer wall is longitudinallytranslatable between a low damping force position where said first gapwidth is different than said second gap width and said third gap widthis less than both said first and second gap widths and a high dampingforce position where said third gap width is greater than both of saidfirst and second gap widths.
 6. The assembly according to claim 5wherein said outer wall includes a stepped inner surface to define saidfirst and second gap widths.
 7. The assembly according to claim 6wherein gap widths between each of said plurality of ports and saidouter wall are varied with respect to each other.
 8. The assemblyaccording to claim 7 wherein said stepped inner surface includes onestep of variable height for each of said plurality of ports.
 9. Theassembly according to claim 1 wherein said actuator is a grip portionformed on an exterior surface of said first cylinder, said grip portionbeing manually translated along said direction parallel to saidlongitudinal path to vary the size of said gap in relation to saidplurality of ports.
 10. The assembly according to claim 1 wherein saidactuator is an electrical control for selectively translating said firstcylinder along said direction parallel to said longitudinal path underpredetermined conditions to vary the size of said gap in relation tosaid plurality of ports.
 11. A shock absorber assembly comprising: afirst cylinder having an outer wall with a thickness defined by aconstant outer diameter and a variable inner diameter; a second cylindermounted within said first cylinder and having an inner wall enclosing achamber and spaced apart from said outer wall to define a gap extendinglongitudinally between said first and second cylinders; a dampingmechanism mounted within said second cylinder to separate said chamberinto a rebound side and a compression side wherein said dampingmechanism moves longitudinally relative to said inner wall for dampingvibrations; and a plurality of ports formed within said inner wall todefine a fluid path wherein fluid flows bi-directionally within said gapand into and out of said rebound and compression sides of said chambervia said ports as said first cylinder is moved relative to said secondcylinder to selectively adjust damping by varying gap size.
 12. Theassembly of claim 11 wherein said outer wall is continuously solid alonga longitudinal length of said first cylinder with said inner diametervarying along the longitudinal length to define a variable innerdiameter to outer diameter profile.
 13. The assembly according to claim12 wherein said inner wall has a ported portion and a non-ported portionwith all of said ports being formed along said ported portion of saidinner wall and wherein said variable inner diameter to outer diameterprofile defines a first gap width between one of said ports and saidouter wall, a second gap width between another of said ports and saidouter wall, and a third gap width between said non-ported portion ofsaid inner wall and said outer wall, said outer wall being rotated toadjust said first, second, and third gap widths to control the dampingforce.
 14. The assembly according to claim 13 wherein said variableinner diameter to outer diameter profile is uniform in cross section;and said outer wall is rotatable between a low damping force positionwhere said first gap width is the same as said second gap width and saidthird gap width is less than both said first and second gap widths and ahigh damping force position where said third gap width is greater thanboth of said first and second gap widths.
 15. The assembly according toclaim 13 wherein said variable inner diameter to outer diameter profileis non-uniform in cross section; and said outer wall is rotatablebetween a low damping force position where said first gap width isdifferent than said second gap width and said third gap width is lessthan both said first and second gap widths and a high damping forceposition where said third gap width is greater than both of said firstand second gap widths.
 16. The assembly according to claim 15 whereinsaid outer wall includes a stepped inner surface to define said firstand second gap widths.
 17. The assembly according to claim 15 whereinsaid outer wall includes a tapered inner surface to define said firstand second gap widths.
 18. The assembly according to claim 11 whereinsaid first cylinder is rotated relative to said second cylinder to varygap size.
 19. The assembly according to claim 11 A shock absorberassembly comprising: a first cylinder having an outer wall with athickness defined by a constant outer diameter and a variable innerdiameter; a second cylinder mounted within said first cylinder andhaving an inner wall enclosing a chamber wherein said first cylindercomprises an outermost shock absorber cylinder and said second cylindercomprises an innermost shock absorber cylinder, said outermost shockabsorber cylinder surrounding a substantial length of said innermostshock absorber cylinder such that said inner wall is spaced apart fromsaid outer wall to define a gap extending longitudinally between saidoutermost and innermost shock absorber cylinders; a damping mechanismmounted within said second cylinder to separate said chamber into arebound side and a compression side wherein said damping mechanism moveslongitudinally relative to said inner wall for damping vibrations; and aplurality of ports formed within said inner wall to define a fluid pathwherein fluid flows bi-directionally within said gap and into and out ofsaid rebound and compression sides of said chamber via said plurality ofports as said first cylinder is moved relative to said second cylinderto selectively adjust damping by varying a size of said gap wherein saidfirst cylinder is axially translated relative to said second cylinder tovary gapa size of said gap.
 20. The assembly according to claim 11wherein said variable inner diameter presents a radially variableprofile.
 21. The assembly of claim 11 wherein said variable innerdiameter varies both in a radial direction and a longitudinal directionalong a longitudinal length of said outer wall.
 22. A method foradjusting damping force in a shock absorber comprising the steps of: (a)mounting a first cylinder having an inner wall defining a chamber withina second cylinder having a solid outer wall with a variable thicknessdefined by a constant outer diameter and a variable inner diameter byspacing the outer wall apart from the inner wall to define a gapextending longitudinally between said first and second cylinders; (b)mounting a damping mechanism within the chamber of the first cylinder todefine a compression side and a rebound side with the damping mechanismmoving longitudinally relative to the inner wall for damping vibrations;and (c) moving the second cylinder with respect to the first cylinder toadjust the size of the gap to selectively change the damping force. 23.The method according to claim 22 including forming a plurality oflongitudinally spaced ports in the inner wall on one side of the firstcylinder to define a fluid flow path wherein fluid flowsbi-directionally within the gap and into and out of the rebound andcompression sides via the ports; defining a first gap width between theports and the outer wall and a second gap width between an opposite sideof the first cylinder from the ports and the outer wall; moving thesecond cylinder such that the first gap width is greater than the secondgap width for a low damping force.
 24. The method according to claim 22including forming a plurality of longitudinally spaced ports in theinner wall on one side of the first cylinder to define a fluid flow pathwherein fluid flows bi-directionally within the gap and into and out ofthe rebound and compression sides via the ports; defining a first gapwidth between the ports and the outer wall and a second gap widthbetween an opposite side of the first cylinder from the ports and theouter wall; moving the second cylinder such that the second gap width isgreater than the first gap width for a high damping force.
 25. Themethod according to claim 22 including forming a plurality oflongitudinally spaced ports in the inner wall on one side of the firstcylinder to define a fluid flow path wherein fluid flowsbi-directionally within the gap and into and out of the rebound andcompression sides via the ports; defining a first gap width between oneof the ports and the outer wall, a second gap width between another ofthe ports and the outer wall, and a third gap width between an oppositeside of the first cylinder from the ports and the outer wall; moving thesecond cylinder such that the first gap width is different than thesecond gap width and the third gap width is less than both the first andsecond gap widths for a low damping force.
 26. The method according toclaim 22 including forming a plurality of longitudinally spaced ports inthe inner wall on one side of the first cylinder to define a fluid flowpath wherein fluid flows bi-directionally within the gap and into andout of the rebound and compression sides via the ports; defining a firstgap width between one of the ports and the outer wall, a second gapwidth between another of the ports and the outer wall, and a third gapwidth between an opposite side of the first cylinder from the ports andthe outer wall; moving the second cylinder such that the third gap widthis greater than both of the first and second gap widths for a highdamping force.
 27. The method according to claim 22 wherein step (c)further includes rotating the second cylinder relative to the firstcylinder.
 28. The method according to claim 22 A method for adjustingdamping force in a shock absorber comprising the steps of: (a) mountinga first cylinder having an inner wall defining a chamber within a secondcylinder having a solid outer wall with a variable thickness defined bya constant outer diameter and a variable inner diameter by spacing theouter wall apart from the inner wall to define a gap extendinglongitudinally between the first and second cylinders and wherein thefirst cylinder comprises an innermost shock absorber cylinder and thesecond cylinder comprises an outermost shock absorber cylinder with theoutermost shock absorber cylinder surrounding a substantial length ofthe innermost shock absorber cylinder such that the gap is formedbetween the outermost and innermost shock absorber cylinders; (b)mounting a damping mechanism within the chamber of the first cylinder todefine a compression side and a rebound side with the damping mechanismmoving longitudinally relative to the inner wall for damping vibrations;(c) forming a plurality of longitudinally spaced ports in the inner wallon one side of the first cylinder to define a fluid flow path whereinfluid flows bi-directionally within the gap and into and out of therebound and compression sides via the plurality of longitudinally spacedports; and (d) moving the second cylinder with respect to the firstcylinder to adjust the size of the gap to selectively change a dampingforce wherein step (c) (d) further includes axially translating thesecond cylinder relative to the first cylinder.
 29. The method accordingto claim 22 wherein the outer wall is continuously solid along alongitudinal length of the outer wall and wherein step (a) furtherincludes defining the variable inner diameter as varying in a radialdirection and a longitudinal direction along the longitudinal length ofthe outer wall to define a variable inner diameter to outer diameterprofile.
 30. A shock absorber assembly comprising: a first cylinderhaving a solid outer wall with a thickness defined by a constant outerdiameter and a variable inner diameter; a second cylinder mounted withinsaid first cylinder and having an inner wall enclosing a chamber, saidinner wall being spaced apart from said outer wall to define a gapextending longitudinally between said first and second cylinders; apiston mounted within said second cylinder to separate said chamber intoa rebound chamber and a compression chamber, said piston beinglongitudinally movable relative to said inner wall to dampen vibrations;a plurality of longitudinally spaced ports formed within said inner wallto define a fluid path wherein fluid flows bi-directionally within saidgap and into and out of said rebound and compression chambers via saidports in response to said piston moving back and forth within saidchamber; and an actuator for selectively adjusting the damping force bymoving said inner and outer walls relative to each other to vary thesize of said gap.
 31. The assembly according to claim 30 wherein saidvariable inner diameter varies in both a radial direction and alongitudinal direction along a length of the outer wall.
 32. Theassembly according to claim 31 A shock absorber assembly comprising: afirst cylinder having a solid outer wall with a thickness defined by aconstant outer diameter and a variable inner diameter wherein saidvariable inner diameter varies in both a radial direction and alongitudinal direction along a length of the outer wall; a secondcylinder mounted within said first cylinder and having an inner wallenclosing a chamber wherein said first cylinder comprises an outermostshock absorber cylinder and said second cylinder comprises an innermostshock absorber cylinder, said outermost shock absorber cylindersurrounding a substantial length of said innermost shock absorbercylinder such that said inner wall is spaced apart from said outer wallto define a gap extending longitudinally between said outermost andinnermost shock absorber cylinders; a piston mounted within said secondcylinder to separate said chamber into a rebound chamber and acompression chamber, said piston being longitudinally movable relativeto said inner wall to dampen vibrations; a plurality of longitudinallyspaced ports formed within said inner wall to define a fluid pathwherein fluid flows bi-directionally within said gap and into and out ofsaid rebound and compression chambers via said plurality oflongitudinally spaced ports in response to said piston moving back andforth within said chamber; and an actuator for selectively adjusting adamping force by moving said inner and outer walls relative to eachother to vary the size of said gap wherein said variable inner diameteris formed with a wave profile having alternating minimum and maximumdiameters.
 33. The assembly according to claim 31 wherein said innerdiameter is formed with a tapered profile tapering from a maximum innerdiameter to a minimum inner diameter along the length of the outer wall.34. The assembly according to claim 31 wherein said inner diameter isformed with a stepped profile with a first inner diameter positioned atone of said ports and a second inner diameter longitudinally spaced fromsaid first inner diameter and positioned at another of said ports withsaid second inner diameter being greater than said first inner diameter.35. The assembly according to claim 31 wherein said outer wall isrotated relative to said inner wall to adjust the size of said gap. 36.The assembly according to claim 31 A shock absorber assembly comprising:a first cylinder having a solid outer wall with a thickness defined by aconstant outer diameter and a variable inner diameter wherein saidvariable inner diameter varies in both a radial direction and alongitudinal direction along a length of the outer wall; a secondcylinder mounted within said first cylinder and having an inner wallenclosing a chamber wherein said first cylinder comprises an outermostshock absorber cylinder and said second cylinder comprises an innermostshock absorber cylinder, said outermost shock absorber cylindersurrounding a substantial length of said innermost shock absorbercylinder such that said inner wall is spaced apart from said outer wallto define a gap extending longitudinally between said outermost andinnermost shock absorber cylinders; a piston mounted within said secondcylinder to separate said chamber into a rebound chamber and acompressive chamber, said piston being longitudinally movable relativeto said inner wall to dampen vibrations; a plurality of longitudinallyspaced ports formed within said inner wall to define a fluid pathwherein fluid flows bi-directionally within said gap and into and out ofsaid rebound and compression chambers via said plurality oflongitudinally spaced ports in response to said piston moving back andforth within said chamber; and an actuator for selectively adjusting adamping force by moving said inner and outer walls relative to eachother to vary the size of said gap wherein said outer wall islongitudinally translated relative to said inner wall to adjust the sizeof said gap.
 37. The assembly according to claim 30 wherein said outerwall has an variable cross-sectional area along a longitudinal length ofthe first cylinder.
 38. The assembly according to claim 37 wherein saidvariable cross-sectional area is infinitely variable between a minimumcross-sectional area and a maximum cross-sectional area.
 39. Theassembly according to claim 37 wherein said variable cross-sectionalarea increases from a minimum cross-sectional area to a maximumcross-sectional area at discrete intervals.